What's the difference between proofreading and copy-editing?

Proofreading

While proofreading, spelling or grammatical mistakes will be detected. The editor will also make sure that all the punctuation is correct and look for obvious stylistic and lexical errors.

Copy-editing

The additional copy-editing of the text is meant to detect any stylistic, syntax, logistic and linguistic errors and to take care of the right composition and flow of the text. The end result is a text that reads well and is fully understandable to the reader.